As low impurity copper concentrates are gradually exhausted and less readily available, greater attention is directed at arsenic-bearing copper ore bodies. This results in an increasing arsenic level in the average copper concentrates that are purchased by smelters. With time, arsenic levels are projected to rise to even higher levels. Due to current limitations on arsenic abatement technology, smelters have an upper limit of average arsenic levels in copper concentrate that is rapidly being approached.
Arsenic in some copper concentrates is found in the mineral arsenopyrite (FeAsS) in which physical separation of arsenic from copper is possible. However, more typically, arsenic in sulphide copper concentrates is present principally in the following minerals:                Enargite Cu3AsS4         Tennantite Cu12As4S13         Tetrahedrite Cu12Sb4S13         
Substitution of some of the copper with iron and substitution of antimony with arsenic within these mineral structures is common. These compounds show that physical separation of arsenic from the copper is not possible because both elements are bound within the same chemical lattice structure. Chemical separation, such as leaching, separates arsenic from copper, but both enargite and tennantite are resistant to chemical attack.
Numerous hydrometallurgical processes have been developed to treat concentrates that are principally chalcopyrite-containing copper concentrates. These hydrometallurgical processes include, for example:                Low temperature processes (<110° C.): for example, the Albion, the Galvanox, and the INTEC Processes;        Medium temperature processes (130 to 170° C.): the Anglo American-UBC Process, the CESL Copper Process, the Dynatec Process, and Freeport McMoran (Phelps Dodge) Process;        High temperature processes (>200° C.): Total Pressure Oxidation and PLATSOL Processes.        
When applied to sulphosalt-containing copper concentrates, all of the above processes suffer drawbacks. In the low temperature processes, the leaching kinetics of the arsenic (As) and antimony (Sb) sulphominerals that contain copper (Cu) are slower than for the copper-containing chalcopyrite mineral. Consequently, leaching times are impractically long and coincide with incomplete copper recoveries from the sulphosalt minerals. For the medium temperature processes, copper recoveries under the specified conditions are compromised as well.
In the case of the high temperature processes, good copper leaching is achievable in a reasonable time frame. However, the nearly complete extent of sulphur (S) oxidation, forming acid, results in a costly process that requires more neutralizing agent for the additional acid generated, and produces high volumes of residue for which specialized storage is required.
Thus, in each of the hydrometallurgical processes referred to above, the recovery of copper from sulphosalt-containing copper concentrates is uneconomical.
Improvements in the recovery of copper from copper sulphide concentrates containing arsenic and recovery of copper from copper sulphide concentrates containing antimony are desirable.